This invention relates to a passive vehicle occupant restraint belt system in which the belt is automatically, easily, and effectively transferred between an occupant-restraining and an occupant-releasing configuration in response to opening and closing movements of a vehicle door.
In recent years there have been many proposals for passive occupant restraint belt systems for vehicles. The most common type are those based on restraint belts, and most of the proposed belt systems include a belt transfer mechanism which is driven by an electric motor or a mechanical lever or gear transmission. In the case of mechanical drives, a motion transmitter is coupled between the belt transfer device and the vehicle body or door for transmitting and amplifying the door opening and closing movements. One such mechanical device, which is capable of moving the restraint belt between the occupant-restraining and occupant-releasing positions in response to a partial opening of the door is shown and described in commonly-owned U.S. Patent Application Ser. No. 950,020 filed Oct. 10, 1978.
As described in the aforementioned U.S. application, a passive restraint belt system in which the restraining belt can be moved between restraining and releasing positions in response to only a partial opening of the vehicle door is preferred. Since the motion transmitter, however, remains coupled to the belt transfer mechanism during the entire door opening movement, the remainder of the door opening movement must be absorbed within the coupling mechanism. This normally requires a complicated mechanism, such as the folding linkage described in U.S. application Ser. No. 950,020. Moreover, mechanisms of this type possess the disadvantages that in the case of accident where the input amplifier or belt transfer mechanism is damaged and thereby unable to move, there may be difficulty encountered in attempting to open the vehicle door.
A greatly simplified mechanism which overcomes these shortcomings is shown and described in commonly-owned U.S. patent application Ser. No. 45,172, filed June 4, 1979; entitled "Input Motion Coupling to a Motion Amplifier for Use in Door-Actuated Passive Seat Belt System." A mechanism is described for transmitting opening and closing motions of the door to the motion amplifier which includes an extendable rod, one end of which is coupled to the motion amplifier and the other end of which, through the action of a spring, engages a bearing surface on the vehicle body or door. The rod moves between a retracted position and an extended position when the door is moved between closed and partway open to move the belt between occupant-restraining and occupant-releasing positions. When the door is moved between partway open and fully open, the rod, which is fully extended, moves away from the bearing surface such that no further door movement is transmitted to the amplifier.